import React, { Component } from 'react'
import './index.css'

export default class Footer extends Component {

  // 全选checkbox的回调
  handleCheckAll = (event)=> {
      this.props.checkAllTodo(event.target.checked)
  }

  // 清除已完成的任务的回调
  handleClearAllDone =()=>{
    this.props.clearAllDone()
  }

  render() {
    const {todos} = this.props
    // 计算已经完成的
    const doneCount = todos.reduce((pre, current)=>{
      return pre+(current.done ? 1: 0)
    }, 0)

    // 计算总数
    const total = todos.length

    return (
      <div className="todo-footer">
        <label>
          <input type="checkbox" onChange={this.handleCheckAll} checked = {doneCount == total? true: false}/>
        </label>
        <span>
          <span>已完成{doneCount}</span> / 全部{total}
        </span>
        <button onClick={this.handleClearAllDone} className="btn btn-danger">清除已完成任务</button>
      </div>
    )
  }
}
